There are various reasons why a ureter may fail totally or in part to carry urine from the kidneys to the bladder. This is a serious medical condition that may be life threatening in its implications. Procedures are known for placing a catheter or stent through the ureter from one end to the other to ensure proper carrying of urine from the kidneys to the bladder. This may be for a short term or for a very long term.
There is a tendency for a ureter catheter or stent to tend to migrate from its position in the catheter, typically from the kidneys to the bladder. This is highly undesireable, and may totally defeat the purpose of the stent. Efforts have been made to prevent such migration, and typically comprise coiling of one or both ends of the stent. A stent is inserted by a quasi-surgical procedure lengthwise from the bladder into the kidneys, and the stent must be straight for this purpose. Accordingly, a stent, which typically is made of silicone is preconditioned to a curve, but it is straightened by an inserting wire or the like. It is often very difficult to tell if the stent end has properly coiled into its premolded position after insertion and after removal of the inserting wire.